A month and a half into iOS6 and apps still haven't been updated for iPhone 5.

What is the deal here? I understand some apps won't be updated just yet but prominent apps like WhatsApp and Quora for example also haven't been updated. I know this has more to do with developers, but Apple was supposedly expediting the approval process for updated apps, yet nothing has been updated.

I still have an app or two that don't even have retina display support.

It's all on the developers. Some apps with a lot of graphics are going to take a long time to update because the developers basically have to make all new images to support the larger screen. That obviously takes time.

Not all devs are well enough funded to bang out an update. In addition, many are reworking their UI's for the bigger screen rather than just elongating the app.

Frankly, I find the devs that simply extend their screen to be slightly lazy. I want ones that think through the entire use case and new hand positioning rather than just showing an extra line or two on a list view.

That said, for simple apps it does make sense. The more immersive apps however need to be rethought for a great experience.

What is the deal here? I understand some apps won't be updated just yet but prominent apps like WhatsApp and Quora for example also haven't been updated. I know this has more to do with developers, but Apple was supposedly expediting the approval process for updated apps, yet nothing has been updated.

Your best bet is to contact the developers of the apps you want updated.
Do you think the readers of the forum can help you? As you know it is up to the developers.

The main thing developers are doing is redoing their apps to take advantage of the autolayout that was added. This will allow them to scale their apps to every screen and aspect ratio. Once they do this, from my understanding, all layouts/resolutions/aspect ratios are covered and it then becomes a simple thing of just bug fixing and updating apps again. Give them time, having a couple black bars for a bit is not a big deal at all.